1. Technical Field of the Invention
The present invention relates to a cement manufacturing apparatus and method, and more particularly to the apparatus and the method capable of increasing quantity of fly ash used in the apparatus while controlling unburned carbon content of cement within a permissible range. 2. Description of the Related Art
Fly ash generated in coal firing power plants and the like has been used for cement admixture, concrete admixture, raw materials for artificial lightweight aggregates, etc. In these cases, since fly ash containing much unburned carbon causes various problems it is necessary to remove the unburned carbon, so that many techniques have been proposed. Particularly, when fly ash is utilized for cement admixture, it is thought that adding wet ash that is obtained after decarbonization by wet flotation to materials fed to a cement mill is the best method to reduce costs of equipment and operation.
Therefore, when utilizing fly ash as a cement admixture, the following method was utilized. The method comprises the steps of: generating slurry by adding water to fly ash; adding frothing agent to the slurry; generating air bubbles while agitating the slurry; causing unburned carbon contained in the fly ash to adhere to these air bubbles; removing the unburned carbon from the fly ash by removing the air bubbles; and grinding the fly ash together with clinker by a cement mill (exemplarily described in patent document 1).
Patent document 1: Japanese Patent No. 3613347 gazette